State what is meant by the capacitance of a parallel plate capacitor.

1. (a)State what is meant by the capacitance of a parallel plate capacitor.[2]
2. (b)A capacitor of capacitance C is connected into the circuit shown in [Figure 7.1]. When the two-way switch is in position A, the capacitor is charged so that the potential difference across it is V. The switch moves to position B and the capacitor fully discharges through the sensitive ammeter. The switch moves repeatedly between A and B so that the capacitor charges and then discharges with frequency f.
3. (b)(i)Show that the average current I in the ammeter is given by the expression I = fCV.[2]
4. (b)(ii)For a potential difference V of 150 V and a frequency f of 60 Hz, the average current in the ammeter is 4.8 µA. Calculate the capacitance, in pF, of the capacitor. capacitance = ........................................................... pF [2][2]
5. (c)A second capacitor, having the same capacitance as the capacitor in (b), is connected into the circuit of [Figure 7.1]. The two capacitors are connected in series. State and explain the new reading on the ammeter. new reading = ........................................................... µA [3][3]

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